Economics of Fungicide Application for Rice Sheath Blight Disease in Arkansas (Year 3).

Sheath blight disease of rice caused by Rhizoctonia solani AG1-1A is one of the major diseases of rice in Arkansas. Fungicides are often recommended if the established threshold levels are reached and the disease progresses into the upper canopy during the later growth stages. The economic benefit of these applications must periodically be reevaluated based on changes in cultivars, management practices, and fungicide efficacy. The effect of fungicide application timing was evaluated on the cultivars LaKast and Jupiter at two seeding rates. The fungicide applications at panicle differentiation and boot split were compared with the untreated controls. All plots were artificially inoculated with R. solani AG1-1A. Both fungicide application timings resulted in reduced sheath blight incidence and higher grain yields when compared to the untreated control. However, mean monetary gains were variable based on trial location and fungicide application timing. With the adequate nitrogen fertilization applied and less differences in canopy, seeding rates seemed to have less impact in the disease or grain yield in this study. These results suggest the current recommended fungicide application timing of panicle differentiation through heading is generally most appropriate for use in Arkansas. [ABSTRACT FROM AUTHOR]